The Thin Film shader that used to work well with legacy isn't doing much (good) with the new physical material.
I'm refering to the attached scene and the image rendered with it:
Top row (please forgive the exaggerated settings to prove my point ;)) shows metals, left a legacy material metal with thin film straight and undiluted in the reflection color.
The next two are physical materials, one with thin film straightly put in the color slot again, the other one with thin film in the clearcoat property where I thought it would make more sense.
In both cases, nothing really happens, thin film-wise.
Bottom row shows dielectrics, left legacy again, next to it two physical materials, one with thin film in the reflection color, the other one with thin film in clarcoat, something happens here, but the result is rather ... unexpected.
Win 10, C4D R23.110, Corona latest available daily.